As one skilled in this art will appreciate, depending on the type of application insecticide, herbicide, bacteriostat, fungicide, pesticide, plant nutrient or other active agent applied to crops and their surrounding environment, a preferred droplet size range and spray output is generally required to maximize the effectiveness of the agent and reduce contamination of surrounding areas.
The Caribbean and the Mediterranean fruit flies are exemplary of the type of pest that can cause major damage to crops, particularly citrus crops, but can be effectively controlled by the timely application of appropriate insecticides compounded with attractant baits. It has been established that insecticides such as malathion when combined in the appropriate ratio with a suitable bait and applied in droplets having a diameter of about 600 microns to about 800 microns are most effective in controlling these pests in citrus orchards. Although such droplet sizes are attainable via aerial application this method is necessarily limited to larger orchards where it may be used most efficiently. Even then, areas adjacent to the spray zone may often be contaminated with pesticide, due to ambient weather conditions and drift of the droplet cloud delivered from the air. In addition, in the case of citrus orchards, it is the tops of the trees that will receive the greatest amount of treatment while the core may receive much less of the aerially delivered spray.
While application of such insecticide bait formulations from tractor driven spray units may provide somewhat more specificity, relative to aerial application, in projecting the spray into citrus orchards, high volume fan driven, lamellar flow, droplet atomization spray units as described in U.S. Pat. No. 4,659,013 produce droplets having an average diameter of about 125 microns while at the same time projecting relatively large volumes of insecticide bait formulation. Thus, this approach lacks efficiency because it does not deliver the optimum droplet size range, while still posing a contamination hazard to adjacent areas.
There is a need for a method and means to more closely control the droplet size and output of sprays delivered ground borne in order to obtain the optimum droplet size range for any agricultural formulation that is delivered. There is a further need to at the same time deliver the spray ground borne in a manner that keeps the output volume of the spray low and comparable to the low volumes known in the art to be delivered aerially, so that the minimum effective volume is projected into the agricultural area requiring treatment without causing undue contamination to adjacent areas. In the particular case of pests, such as the Caribbean and the Mediterranean fruit flies, whose propagation can cause widespread damage to citrus crops, a means and method is needed to deliver baited insecticidal formulations in the droplet size known in the art to be most effective in their eradication while at the same time keeping contamination of adjacent non-targeted areas to a minimum. There is a still further need to deliver ground borne the droplet size and volume per acre, of baited insecticide formulations and other agriculturally active substances, currently achieved by aerial delivery so that crops can be treated without the restrictions of weather, daytime application imposed by aerial delivery.